We propose to use event-related brain potentials (ERPs) and transcranial magnetic stimulation (TMS) to examine the mechanisms associated with a particular abnormality of spatial attention in schizophrenia: increased facilitatory and decreased inhibitory priming at short prime-target intervals. We propose that abnormal spatial priming in schizophrenia is related to a dysfunction of an early inhibitory mechanism in prefrontal cortex. To test this hypothesis we will study the performance of schizophrenic and matched healthy individuals in a standard spatial priming task, using ERPs and TMS respectively to examine the stages of processing and brain areas involved. We predict that: 1) Relative to controls, schizophrenic participants will display abnormal spatial priming effects on overt responses (reaction time and accuracy) at the short prime-target interval. 2) Spatial priming effects on the P1 ERP component will be reduced in schizophrenia patients relative to controls at the short prime-target interval, consistent with impaired early inhibitory control. 3) In a subset of the healthy participants, prefrontal as opposed to parietal TMS will produce similar abnormal priming effects on overt responses as found for the patients, consistent with dysfunction of an early prefrontal mechanism. We hope that these results will advance our understanding of the neurocognitive bases of schizophrenia and ultimately contribute to the treatment of this disorder.